Mackay was best known for a highly successful playing career with Heart of Midlothian, the Double-winning Tottenham Hotspur side of 1961, and winning the league with Derby County as a manager.

Mackay was a talented all-round player; a strong tackler, physically fit and had good technique with the ball.

After signing Alex Young and Bobby Kirk, Walker's side proceeded to win the 1955–56 Scottish Cup.

Just over a month after he regained his place in the first team, Mackay again played Queen of the South this time in a 2–1 home league win on 7 March 1959.

[14] The league game against QoS was Mackay's last for Hearts after they accepted a bid of £32,000 from Tottenham Hotspur for their captain.

In Hearts' next game Mackay's vacated half back berth was taken by George Thomson, who moved from inside forward.

Thomson's inside forward spot was given to debutant Bobby Rankin, who had been signed for £4,000 from Queen of the South two days before Mackay's last Hearts game.

On 10 December 1963 Mackay broke his left leg in a challenge with United's Noel Cantwell after eight minutes of the return tie at Old Trafford.

[26] In the subsequent Charity Shield, Spurs drew 3–3 with Manchester United in a match remembered for goalkeeper Pat Jennings scoring with a kick from his own penalty area.

None of these trophies were won in the two seasons affected by Mackay's lengthy injury due to his leg break.

In his first season at the Baseball Ground, in which the club gained promotion to the First Division, he was chosen FWA Footballer of the Year, jointly with Manchester City's Tony Book.

[29] When he was a player at Derby County, Clough made Mackay play in a sweeping role and used his influence on the team to encourage them to turn defence into attack through a passing game.

Aged 36, he joined Swindon Town in 1971 as player/manager where he stayed one season before he retired as a player and focused solely on management.

[30] Aged 22, Mackay made his debut for Scotland on 26 May 1957 in a qualifying game for the 1958 World Cup, against Spain at the Bernabéu Stadium in Madrid.

Scotland qualified for the tournament in Sweden, with Mackay playing a single game, on 15 June 1958, against France; a 2–1 defeat at the Eyravallen Stadium in Örebro.

[32] Mackay then spent two years out of the side, with Jim Baxter and Pat Crerand usually being the preferred half back pairing.

Mackay was recalled two years later in April 1963, again versus England at Wembley, but this time Scotland won 2–1.

In his two years out the team Mackay missed the entire qualification campaign for the 1962 FIFA World Cup (Scotland were eliminated in a play off by the eventual tournament runners-up, Czechoslovakia).

He made 22 national appearances, his last coming on 2 October 1965, again in the British Home Championships, a 3–2 away defeat to Northern Ireland.

[31] In 1971 Mackay was appointed player-manager of Swindon Town but left after just one season to take charge of Nottingham Forest.

[34] Mackay's reign at Belle Vue lasted until March 1989[35] before he moved to Birmingham City, who had just been relegated to the third tier of the league for the first time in their history.

[39] Mackay appears as a character in David Peace's novel The Damned Utd, a fictionalised account of Brian Clough's time as manager of Derby County and Leeds United.

[40] George Best (1946–2005), of Manchester United, one of Tottenham's fiercest rivals in the 1960s, described Mackay as "the hardest man I have ever played against – and certainly the bravest".

[42] Heart of Midlothian stated "It is with deep regret that we have to advise of the death of Dave Mackay who was possibly the most complete midfield player that Scotland has ever produced".

[43] Tottenham wrote in an obituary "Dave Mackay will certainly always be remembered here as one of our greatest ever players and a man who never failed to inspire those around him.